Often agents may not have clear-cut distinguishability criteria.
For example, an agent may categorize light frequencies into basic colours such as green and blue — there may be some frequencies that the agent could file as both green and blue. In the language of PBR [1]}, the reduced states “blue” and “green” would be epistemic and not ontic (with respect to the underlying state space of frequencies \(\Omega \) ).
Agents could also have a notion of approximate distinguishability, for example of the sort “I can distinguish these two states with probability \(1-p\) .”
